1. Field of the invention
The present invention relates to the field of power electronics. It relates, in particular, to a cooled high-power semiconductor device comprising
(a) a disk-shaped semiconductor substrate; PA1 (b) one contact disk which is arranged parallel to the semiconductor substrate and spaced from it on each of the two sides of the semiconductor substrate; PA1 (c) a multiplicity of mutually parallel contact filaments which are connected, by a materially continuous joint, on one side to the associated contact disk and on the other side to the semiconductor substrate between each contact disk and the semiconductor substrate. PA1 (d) cooling channels are present between the contact filaments, through which cooling channels a coolant flows; PA1 (e) the terminating edge of the semiconductor substrate is provided with a passivation; and PA1 (f) the other free faces of the semiconductor substrate are directly in contact with the coolant.
Such a device is known, for example, from the publication U.S. Pat. No. 4,333,102.
2. Discussion of Background
High-power semiconductor devices (diodes, thyristors, GTOs etc.) from about 200 A current level upwards are distinguished by large-area Si substrates which cannot be readily contacted by materially continuous joints (for example by solder joints) since silicon and the metallic contact parts have very different thermal expansions.
For this reason, the so-called pressure contact housing in disk form (disk-type package) is normally used for packaging such devices (in this connection see, for example, the publication U.S. Pat. No. 4,402,004). In such a disk-type package, the electrodes of the Si substrate are contacted nonpositively by pressure loading, it also being necessary to remove the heat loss of the device via these pressure contacts.
The thermal resistance of a pressure contact housing is due to the parting lines present between the parts pressed onto one another. An elaborate pressure frame is therefore necessary to clamp the devices to the heat sinks in a thermally efficient manner. In addition, the Si substrate has to be accommodated in an elaborate, hermetically sealed ceramic housing.
To improve the heat removal while neutralizing the heat expansion effects at the same time, it has now been proposed in the publication mentioned in the preamble to arrange, between the semiconductor substrate and the external heat removal disks, twisted bundles of wire which are joined by a materially continuous joint (soldered) both to the substrate and also to the respective heat removal disk.
Although an external pressure is no longer needed in this arrangement and the heat resistance with respect to the environment is reduced, the heat loss nevertheless has to be conducted completely through the bundles of wire. In addition, a hermetically sealed ceramic/metal housing continues to be necessary.